Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
dung dai » duong dai, dung tai, dung dat
van dung » van dong, xay dung, tin dung
cac tac » cac toc, cac bac, cac dac
cac tuc » cac toc, cac tu, cac nuoc
sach ty » sach tu, sach thu, xach tay
nang mo » nang meo, nang ma, nang co
mo hoc » mon hoc, co hoc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) or (sach y)) nang mo hoc. hieu qua ((cac tuc) OR (cac tac)) van dung dai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang mo hoc. hieu qua ((cac tuc) OR (cac tac)) van dung dai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach y)) nang mo hoc. hieu qua ((cac tuc) OR (cac tac)) van dung dai cua triet".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang mo hoc. hieu qua ((cac tuc) OR (cac tac)) van dung dai cua triet*.